2. Our Imperfect Hearing

We don't really hear the world as it really is.



This graph is called the "Fletcher-Munson curves", after the researchers who came up with it in the 30's or sometime back then. On the horizontal axis are the frequencies of the human hearing range (20Hz-20kHz). On the vertical axis is the actual sound pressure level. The curves show how we perceive the loudness of different frequencies. They came up with the term "phon" to a unit of perceived loudness. Each curve is at the same perceived loudness level. This means it takes 75dB of sound pressure @ 20Hz to sound as loud as 10dB @ 1500Hz. People are most sensitive to sounds between 1kHz-5kHz. These are the main frequencies of speech, so it kinda makes sense. We're least sensitive to stuff below 100Hz and above 10kHz. Another thing you can take away from this chart, is that around 90dB is where we hear the most evenly, which makes it an ideal volume to mix at. Low volumes can be good for checking if all the main instruments are prominent and balanced. High volumes are best for checking if you have too much reverb.